This invention relates to negative resist materials for generating resist patterns by application of high energy radiation such as electron beams or X-rays.
Fabrication of printed and integrated circuitry generally includes one or a series of processing steps in which surface regions are pattern delineated by selective material removal. Such removal, whether accomplished by use of chemical reagents, either acidic or basic, or by machining, for example, ion milling, utilizes masks or "resists". Such resists, generally adherent to the surface being processed, in accordance with this procedure define a negative image of the pattern to be delineated.
In accordance with general practice to date, resist patterns are generated in light sensitive coatings by flooding with ultraviolet light through a master mask in contact with or spaced from the coating, followed by development in an agent which differentiates between exposed and unexposed material.
However, along with the demand for finer and more complicated patterns, it has been found that there exists an essential limit in the pattern forming technique using ultraviolet light and light sensitive materials. To remove this limit and to meet such demand, a new pattern forming technique is being developed and practically applied which uses electron beams and electron beam sensitive materials, or X-rays and X-ray sensitive materials.
According to such technique using X-rays or electron beams, as compared with the conventional method using ultraviolet light, there can be obtained finer patterns and the possibility exists that the pattern accuracy will be increased. However, since the said technique requires an expensive equipment, it is necessary that the production be made in a highly efficient manner. Especially as to radiation sensitive materials, those superior in sensitivity are required. To attain a high pattern accuracy, moreover, it is necessary to provide materials which are superior in contrast. In addition, various other conditions are required of radiation sensitive materials such as operationability, e.g. thin film formation, film quality, e.g. adhesion of coating to substrate as well as its thermal stability and etch-resistance, and shelf like.
Heretofore there have been proposed many radiation sensitive materials for the pattern formation using electron beams and X-rays. However, a material which satisfies the aforesaid conditions, particularly both sensitivity and contrast, has not been known yet.
Polysiloxane with a vinyl group attached to a silicon atom in the main chain is known as a material for pattern formation using electron beams. However, since the main chain is a nonorganic chain, such polysiloxane is inferior in its adhesion to substrate, and the resulting pattern is coarse.
Conventional vinyl group-containing polymers, moreover, show the tendency that an attempt to form a pattern at high speed results in lowering of resolution and that the pattern formed is inferior in accuracy. Such polymers are further disadvantageous in that an attempt to increase sensitivity causes lowering of stability, that the performance is debased during storage and that they are easily affected by visible rays.
It is an object of this invention to overcome the abovementioned drawbacks.
it is another object of this invention to provide new negative resist materials useful for ultrafine pattern generation on exposure to high energy radiation such as electron beams or X-rays.
Other objects of this invention will become apparent from the following description.